Stable operation of microwave plasma generator with a good efficiency of power transfer to the plasma needs to take into account a few of
important factors. Namely the geometry of the wave launching region and discharge conditions. This report include experimental results on influence
of this factors on the tuning characteristics of an atmospheric pressure Surfaguide-type plasma generator.
Streszczenie. Praca zawiera wyniki eksperymentalnego badania wpływu geometrii obszaru sprzęgania i warunków wyładowania na charakterystyki
strojenia generatora plazmy typu Surfaguide. Od czynników tych zależą stabilna praca generatora plazmy i korzystny energetycznie transfer mocy
mikrofal do plazmy. (Wpływ geometrii i warunków wyładowania na charakterystyki strojenia generatora plazmy typu Surfaguide).
Keywords: atmospheric pressure discharge, microwave plasma, plasma generator, Surfaguide.
Słowa kluczowe: wyładowanie pod ciśnieniem atmosferycznym, plazma generowana mikrofalowo, generator plazmy, Surfaguide.
Introduction
Since seventies of the twentieth century when the
surface wave sustained discharges were discovered as a
new plasma source [1], they find practical applications in
various fields. The most common are light sources, neutral
and active species sources, surface treatment reactors,
reactors for chemistry, deposition, etching etc. Today they
are still of high interest. One of the promising application is
the hydrogen production [2, 3]. Wide range of applications
demands appropriate surface wave plasma generator
suitable to operate under different discharge conditions.
Stable and repeatable operation of such plasma generator
with a high efficiency of power transfer to the plasma needs
to take into account its geometry as well as discharge
conditions [4, 5]. In our experimental study we investigated
the influence of that factors on the tuning characteristics of
the Surfaguide-type [6] plasma generator. Surfaguide is the
waveguide based[...]

Plasma (ionised gas) is an object of interest of research
centres and commercial companies. Nowadays, from
industry point of view, there is a growing interest in not
expensive plasma sources for plastic, metal, glass and
composite surface modifications. The plasma treated
material changes its surfaces properties. For example, as
a result of plasma treatment an increase of surface’s
adhesion potential can be obtained. Due to plasma
modification hydrophobic and hydrophilic surface properties
can be established. Using plasma it is also possible to coat
material surface with protecting layer or layer of specific
characteristics. So, plasma surface treatment can be used
in surface cleaning, activating and coating and can be
applied for example in cosmetic packaging, medical
implants or cars parts [1-9]. In addition to the above,
recently, attention is paid to the reduction of investment as
well as operating costs of the surface treatment process.
The importance of small devices, with low energy
consumption, are increasing. Thus the so called
“downsizing" is also a recent trend in a plasma science and
engineering. Recently existing flame conventional devices
dedicated to surface treatment on one hand are not
environmentally friendly, on other hand can cause treated
surface overheating leading to treated surface deformation.
Meanwhile the plasma of moderate temperature is
preferable. Against, applied radio frequency (RF) based
methods of plasma surface modification are of high cost
which further increases investment and operating costs. In
this case one of the way is to use a microwave (2.45 GHz)
frequency plasma at atmospheric pressure. Operating at
atmospheric pressure eliminates an expensive vacuum
apparatus. Using standard microwave frequency of 2.45
GHz allows to use cheap commercial magnetron such as
that installed in microwave oven.
Therefore, to fulfill industry expectations of low cost
source of non-thermal [...]

Nowadays industry is highly interested in various
surface treatment. Plasma surface treatment methods
include processes like: cleaning, activating, etching the
surface. These processes are used as pre-treatment of
metal and plastic surfaces for further processes such as:
soldering, gluing, painting, print. In contrast to chemical
methods, the plasma methods do not require the chemical
agents (solvents, acids, alkalis) and large amounts of water,
so they are friendly to environment [1-3]. Plasma surface
treatment methods also include such processes as: surface
modification, surface coating, and thin film deposition. Using
plasma methods allows to significantly change the
properties of only the surface of materials without changing
their properties at the greater depths. Plasma methods can
be used for the processing of metals, polymers, glass and
fibres, both natural and synthetic. They are used to change
the surface properties such as wettability, adhesion,
hardness, scratch resistance, permeability, corrosion
resistance and others. [4-7]. Plasma surface treatment
methods are used in the electronics, automotive,
aerospace, textiles and biomedical industries (e.g.:
implants) [8-11].
As a response to demand of industry recently we
presented a novel compact microwave (2.45 GHz) plasma
device for surface treatment [12, 13]. However the
knowledge about plasma properties is necessary for
development of plasma surface treatment technology.
Optical emission spectroscopy (OES) is a powerful and
useful tool in the characterization of plasma [14].
Fig. 1. The experimental setup for spectroscopic study of argon microwave atmospheric pressure plasma-sheet.
PRZEGLĄD ELEKTROTECHNICZNY, ISSN 0033-2097, R. 94 NR 7/2018 91
Experiments
The plasma was generated in waveguide-supplied
microwave plasma-sheet source (MPS) operated at 2.45
GHz. Investigated MPS[...]

This paper presents results of study of dry reforming of kerosene using a microwave plasma. The plasma was generated in waveguide
supplied metal-cylinder-based nozzleless microwave plasma source (MPS) operated at 915 MHz. The rotational temperature of heavy species
(assumed to be close to gas temperature) was up to 5500 K (for plasma without kerosene). The hydrogen production rate was up to 470 NL[H2]/h
and the energy efficiency was 89.5 NL[H2] per kWh of absorbed microwave.
Streszczenie. Artykuł przedstawia wyniki badań suchego reformingu nafty w plazmie mikrofalowej (915 MHz). Temperatura rotacyjna cząstek
ciężkich (przyjmowana jako zbliżona do temperatury gazu) wynosiła do 5500 K (dla plazmy bez dodatku nafty). Uzyskana wydajność produkcji
wodoru wynosiła do 470 NL [H2]/h, natomiast efektywność energetyczna do 89,5 NL [H2] na kWh zaabsorbowanej energii mikrofal. (Produkcja
wodoru na drodze suchego reformingu nafty w plazmie mikrofalowej).
Keywords: microwave plasma, hydrogen production, kerosene dry reforming.
Słowa kluczowe: plazma mikrofalowa, produkcja wodoru, suchy reforming nafty.
Introduction
The greenhouse effect from CO2 emissions exhorts
searching of new energy sources meeting the requirements
of being environment-friendly. Hydrogen which has a high
heating value per unit mass (120 kJ/g) and does not
produce CO2 in its combustion is a promising future energy
carrier. Hydrogen is produced by many methods [1]. The
conventional technologies of hydrogen production like coal
gasification, hydrocarbon reforming and water electrolysis
are well developed. Large scale catalytic hydrogen
production has been successfully operating in industry for
many decades. Currently it is the most developed and
economical technique for hydrogen production. Alternative
plasma technologies are very promising for hydrogen
production using hydrocarbons conversions. Plasma
ensures high chemical reactivity environment allowing to
avoid expensive an[...]